Fish retention structure



FIG. 1 is a perspective view of the fish retention structure showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a front view thereof, the back view being the same; and,

FIG. 5 is a right side view thereof, the left side view being the same. 

The ornamental design for a fish retention structure, as shown and described. 